Flexible drive members (i.e. “flexible members”), including belts, chains, wires, and cables, are employed in a wide variety of devices to transmit mechanical power. One example of such a device that typically employs at least one flexible member is that of ah inkjet printer, wherein a flexible member can be employed to move and position the print head.
A typical flexible member is configured to be coupled, or wrapped at least partially around, one or more pulleys, or rollers, or sprockets, or the like. In order to function properly, at least some tension is generally maintained in the flexible member to prevent various undesirable effects associated with inadequately tensioned flexible members. Such undesirable effects can include slippage of the flexible member relative to the pulleys and the like.
Oftentimes, a mechanical power source, such as an electric motor having an output shaft with a pulley attached thereto, is coupled with a flexible member and is employed to drive or circulate the flexible member. In this manner, the mechanical power, and/or motion, produced by such an electric motor can be transmitted by the flexible member to another object or device.
Inasmuch as a considerable amount of tension must be maintained in the flexible member in some situations, such as in the case of a smooth or “friction” flexible member, the electric motor output shaft and/or the shaft bearings must be of an adequate size to withstand not only the forces produced by the output power of the motor, but also to withstand the additional forces resulting from the tension in the flexible member.
That is, at least in some situations, the force resulting from tension in a flexible member of a given system can have a considerable effect on the required size of the motor for that system. That is, in some systems that employ a tensioned flexible member, the size of a motor employed to drive the flexible member is generally specified front the standpoint of ensuring that the motor bearings and/or motor shaft are not overstressed by the additional forces resulting from the tension in the flexible member.
One result of this can be that oversized motors (i.e. motors having excessive power capacity) are utilized in systems employing relatively high-tensioned flexible members simply to ensure that the motor bearings and/or motor shaft are adequate for the forces produced by the tension in the flexible member. This results in inefficient use of motor capacity.